Cathode for electrolytic cells.



F. NICDONALD.

CATHODEVFOR ELECTROLYTIC CELLS.

APPLICATION FILED Aus.5, 191s.

191673115, Patented Jan. 11, 1916.

2 SHEETS-SHEET 1.

F.. NICDONALD.

CATHODE FOR ELECTROLYTIC CELLS.

. APPLxcATloN man Auas, 1915.

@51.` Patented 1311.11, 1916.

2 SHEETS-SHEET 2.

man m CATHODE FOR 'ELECTRGLYTC CELLS.

implication filed August 5, i915. Serial No.

To all whom t may concern:

Be it known that l, Frown MCDONALD, o. citizen of the United States residing et Roaring Spring, in the county of Ble-ir and State of Pennsylvanie, have invented cel1- tain new 'und useful linprovenients in Cetliodes for Electrolytic Cells; and I do declare the following to be a full., clear, end exact description oi the invention, such as will enable others skilled in the ort to which it oppertains to ineke and use the seine.

rlhis invention relates to improvements in cetliodes iior electrolytic cells end more porticularly to cells of the diaphragm type.

The object of 'the invention is to provide o cathode for electrolytic'cells of the die plirogin type `which is free from the objec tionablo features of metallic cethodes.

lt is Well known that all the commercial grades ot salt contain varying amounts of alkaline earths particularly those of celciurn and inognesiuin and when o solution of sodium chlorid is decomposed by the action of the electrical current in a cell of the diaphragm type for the commercial pro duction of caustic sode and chlorin gos, the chlorin gos is set free at the anode and the sodium et the cathode Where it immediately reacts upon the Water contained in the cath-a ode chsn'iber, forming caustic sode. Concurrently with this operation any insoluble salts of calcium or megnesiuni which might be contained in the brine, es impurities, is deposited on the metallic cathode and as this deposit is e. non-conductor of electricity it gradually increases the internal resistance of the cell, thereby necessitating on increase ot power required to operate the cell. rlhis deposit also closes the perforations in the metallic cetliodes und these periioretions are necessary to permit the diffusion. of the caustic sode into the cathode chamber. Con sequently the closing ot these .pertorntions lowers the current eiliciency of the cell.

This invention is devised to overcome these objectionable features of metallic enthodes and consists ,in forming e cathode of cerbonnceous materiel which While being e good electrical conductor is not affected by the Jroducts of electrolysis and to which the elli-aline earths do not adhere", seid cerths remaining in e, free condition indeiii'iitely when such e cathode is employed.

i lilith this end other objects in view the invention consists et certain novel critures of cons Jion sind the conibinetion and orrongenient ot ports es will be hereinafter more fully described and claimed.

ln thenccoinpnnying drawings: Figure l represents a, longitudinal section through an electrolytic cell equipped with this improved cathode; 2 is a` plan view thereof; Fig. 3 is a longitudinal section teken on the line BMS of Fig. 2; Fig. l is o transverse section taken on the line Ll ilof Fig. 2

ln the embodiment illustrated this im proved cathode is shown applied to on electrolytic cell ot' the vertical diophrign type employed for the electrolysis or sodium enlorid in the tori'n on aqueous solution or brine' As shown this cell comprises e con taining tank or receptable l composed of iron or other suitable metal provided with o cement lining;1 2. This tank l is equipped vvth :in overiow pipe 3 for innintni ing e constant electrolyte level in the cathode compartment olf the tank, seid pipe being shown extending through one 'side Woll. oi the tenir Fig.; 2). Disposed .vitliin the tank l ere the cet-hotles which ere preterzibly composed of graphite or other suit able cerboneceons material adapted for the purpose and are connected at tncir upper ends by o negative bus bar' 5 which is secured thereto by connecting' bolts 6. Suitoblc'nonconductive geleitet-,s 7' preferably con'rpose7 oiE asbestos are shown arranged between the plates (see llig. 5l) and the upper ends or". these plates rebbcted shown et 8 the reduced portions 9 of which projectabove the caustic solution curr-led by the tenlr. rl he cathode plates 'which for; i the chambers l0 in the tank ore spaced o suitable distance :troni the side wolle of the tenir and e cement bottoni ll projects u .voirdly between the lotes l opposite sides ot the tenlr und holds theni in spaced relation, seid graphite plates being secured to said bottom by ineens of rods l2 which extend tronsversly through seid bottoni and through the plates at opposite sides thereof (see lligsl). The upper ends of these plates which are robbcted es shovv'n ot 8 provide for the mounting there on of e suitable c ver i3 'which may be coinposed of any scid-prooi material preferably of slate. rlhis cover 13 is formed with n plurality of centrally arranged longitudin nelly elined openings Ll to receivethe lending in rods l5 etteched to the upper ends oif the onodes lo 'i on t cement bottoni ll which :I e pistes spart end forms the lower ends of which, ere

the bottom of the anode chamber. The ends of the anode chamber are closed by upright plates 26 which may be of glass, rubber or other suitable non-conducting material and which extend above the tank 1 and are provided on their inner -faces with laterally extending flanges 27 to form seats for-the ends of the cover member 13. A glass funnel 17 has the stem orshank 18 thereof inserted through an aperture in the cover 13 and extends into the anode chamber whereby the brine or other electrolyte may be con-- veniently poured into said anode chamber. 'lhe leading in rods 15 of the anodesl are connected at their upper ends above the top 13 by a positive bus bar 19. The negative bus bar with which the cathodes are connected and Athe positive bus bar 19 connected with the anodes serve to properly place the anodes and cathodes in circuit.

The portions ofthe cathode plates belowr the rabbets, 8 therein which are designed to be submerged in the caustic solution are made porous by means of saw-cuts 20 to provide for the diffusion of the caustic solution in the cathode chamber. Arranged adjacentthe sides of the cathode plates which are disposed next to the anodes is the porous diaphragm 21 which is preferably composed of sheets of asbestos having their lupper edges bent laterally outward at right angles to form flanges 22 which are designed to rest on'the rabbeted portions 8 of the cathode plates and be clamped thereon by the lower or inner edge of the cover 13 for the 'anode chamber.

While the cathode plates are shown. arranged vertically in the cell it is-supposed to be understood that they need not be necessarily so arranged but may be placed in an inclined or horizontal position without in any way departing from the scope of the invention.

Having fully set forth the structural details of the invention the operation thereof is as follows: The anode compartment having been filled with brine until the highest level thereof is attained, the funnel 17 being used for this purpose, the cathode compartment is filled with a caustic solution, its level bepipe 3. When the cell thus equipped is placed in an electric circuit the current will Y flow from the positive wire 24 to bus bar ,191,k

from the latter to the anodes 16 throughthe electrolyte in the anode chamber lto and through the porous diaphragm 21 to the graphite cathodes 4l, through bus bar to the negative wire 24. This current owing to the fact that the chlorin is an electronegative element causes an evolution of the -latter at the anodes 16 where it collects in the chamber formed above the electrolyte and from whence it is conveyed through a pipe 25 to any desired point. The sodium element being electro-positive is deposited at the. negative pole or cathode and is liberated in the form of sodium and the sodium thus liberated reacts with thev water to form caustic soda andfree hydrogen gas.

It is of course to be understood that in practice as many of thealternate compartments of anodes and cathodes as may be desired may be built up together and that yvarious changes in the form, proportion and the minor details of construction may be resorted to without departing from the prin- Vciple or sacrificing any of the advantages of the claimed invention.

I claim as my invention:

1. A cathode for an electrolytic cell composed of a graphite plate having its upper end rabbeted and the portion thereof below said rabbetiprovided with transversely extending slots.

2. A cathode for an electrolytic cell composed of a graphite plate having its upper end rabbeted and the portion thereof below said rabbet provided with transversely extending slots, a bus bar connecting the reduced upper ends of said cathodes, and insulating gaskets arranged between the graphite plates.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

I FRANK MCDONALD. IVitnesses: v

R. D. LORENZ,

J. I). MARTIN.

Copies 0f this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C.- 

